Source code for openquake.hazardlib.gsim.campbell_1997

# -*- coding: utf-8 -*-
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"""
Module exports :class:`Campbell1997`
"""
import numpy as np

from openquake.hazardlib.gsim.base import GMPE
from openquake.hazardlib import const
from openquake.hazardlib.imt import PGA


[docs]def get_fault_term(rake): """ Returns coefficient for faulting style (pg 156) """ rake = np.where(rake < 0, rake + 360, rake) f = np.zeros_like(rake) f[(rake >= 45) & (rake <= 135)] = 1. f[(rake >= 225) & (rake <= 315)] = .5 return f
[docs]def get_Ssr_term(vs30): """ Returns site term for soft rock (pg 157) """ return (vs30 >= 760) & (vs30 < 1500)
[docs]def get_Shr_term(vs30): """ Returns site term for hard rock (pg 157) """ return vs30 >= 1500
[docs]class Campbell1997(GMPE): """ Implements GMPE (PGA) by Campbell, Kenneth W. "Empirical near-source attenuation relationships for horizontal and vertical components of peak ground acceleration, peak ground velocity, and pseudo-absolute acceleration response spectra." Seismological research letters 68.1 (1997): 154-179. """ #: Supported TRT active...we specify active_shallow_crust DEFINED_FOR_TECTONIC_REGION_TYPE = const.TRT.ACTIVE_SHALLOW_CRUST #: Supported intensity measure types are PGA, PGV, PSA, but we only define #: PGA because this is the only IMT used by an implemented model (09/18) DEFINED_FOR_INTENSITY_MEASURE_TYPES = {PGA} #: Supported intensity measure component is the horizontal component DEFINED_FOR_INTENSITY_MEASURE_COMPONENT = const.IMC.AVERAGE_HORIZONTAL #: Supported standard deviation type is only total, see equation 4, pg 164 DEFINED_FOR_STANDARD_DEVIATION_TYPES = {const.StdDev.TOTAL} #: Requires vs30 REQUIRES_SITES_PARAMETERS = {'vs30'} #: Required rupture parameters are magnitude and top of rupture depth REQUIRES_RUPTURE_PARAMETERS = {'mag', 'rake'} #: Required distance measure is closest distance to rupture. In the #: publication, Rseis is used. We assume Rrup=Rseis, justified by #: our calculations matching the verification tables REQUIRES_DISTANCES = {'rrup'} #: Verification of the mean value was done by digitizing Figs. 9 and 10 #: using Engauge Digitizer. The tests check varied magnitude, distance, #: vs30, and faulting type. Maximum error was ~1.3%. OpenQuake trellis #: plots match these figures. Also tested against a matlab implementation #: (web.stanford.edu/~bakerjw/GMPEs/C_1997_horiz.m), which also has no #: verification tables.
[docs] def compute(self, ctx: np.recarray, imts, mean, sig, tau, phi): """ See :meth:`superclass method <.base.GroundShakingIntensityModel.compute>` for spec of input and result values. """ R = ctx.rrup M = ctx.mag # get constants Ssr = get_Ssr_term(ctx.vs30) Shr = get_Shr_term(ctx.vs30) rake = ctx.rake F = get_fault_term(rake) # compute mean mean[:] = -3.512 + (0.904 * M) - ( 1.328 * np.log(np.sqrt(R**2 + (0.149 * np.exp(0.647 * M))**2))) \ + (1.125 - 0.112 * np.log(R) - 0.0957 * M) * F \ + (0.440 - 0.171 * np.log(R)) * Ssr \ + (0.405 - 0.222 * np.log(R)) * Shr # standard deviations from mean (pg 164; more robust than # estimate using magnitude mean = np.exp(mean) sig[:] = 0.39 sig[mean < 0.068] = 0.55 idx = np.logical_and(mean >= 0.068, mean <= 0.21) sig[idx] = 0.173 - 0.140 * np.log(mean[idx])